Numerous problems have been encountered in both the manufacture and use of conventional fitted sheets. Conventional fitted sheets typically employ various combinations of seams and/or elastic bands at the corners. The contoured corners thus formed are intended to fit snugly over the corners of an underlying mattress whenever the sheet is in use. Unfortunately, although most mattresses come in lengths and widths that are fairly standard depending upon whether the mattress is twin, full, queen or king size, the thicknesses of the mattresses can vary greatly even for a given type. Such variations are attributable to the methods and materials of construction, including factors such as whether the mattress is foam or innerspring, the type of coil construction for innerspring mattresses, the type and amount of padding, the cover material and stitching patterns, and the welting utilized along the edges between adjoining mattress surfaces. The effective length and width of a mattress can also vary to a lesser extent depending upon the materials and methods of construction utilized.
Because bed linen manufacturers generally produce fitted sheets having a single set of dimensions for each standard bed size, difficulties frequently arise when the sheets are used by the consumer. When the fitted sheets are placed over a relatively thinner or smaller mattress, the corners may not fit snugly, causing the sheet to bunch or wrinkle across the bed surface, making the bed uncomfortable and unattractive. When the sheets are used with relatively thicker or larger mattresses, it is often difficult to stretch the last corner over the mattress, and ripping or tearing of the corner construction may occur, particularly after repeated use and laundering.
Conventional fitted sheets are disclosed, for example, in U.S. Pat. Nos. 3,181,179 and 3,694,832. U.S. Pat. No. 3,181,179 discloses fitted sheets having shoulders cut on each end and side panel which are subsequently sewn together and bordered with elastic strips on their open edges. U.S. Pat. No. 3,694,832 discloses fitted sheets wherein triangular pieces of material are removed from the end and side panels, and the remaining material is folded and sewn to obtain the shaped or fitted corners.
U.S. Pat. No. 4,045,832 discloses an improvement in fitted sheets that provides a greater degree of adjustability through the use of overlying flaps having releasable strips made of a material such as Velcro. The corners are constructed with cutouts through which a portion of the mattress corner extends when the sheet is in use. However, the sheets disclosed in U.S. Pat. No. 4,045,832 are constructed using stitched darts in combination with the partially open corners and the releasable closure strips.
The use of stitched darts and/or elastic to form the fitted corners as disclosed in the foregoing patents requires the use of manufacturing procedures that are more complicated and expensive than would be needed if such stitching were not required. Furthermore, sheets made in such manner cannot be laid out flat, and are therefore more difficult to fold, package and store.
The use of Velcro fasteners with sheets is also disclosed in U.S. Pat. Nos. 3,832,743 and 4,241,466. These patents disclose the use of releasable fasteners for separably fastening one edge of a top sheet to a side or end panel of an underlying bottom sheet to prevent the top sheet from coming loose or untucked during use.
Problems have also been encountered with pillow cases in that pillows can work back out the open ends through which they are inserted during use. Particular concerns arise with pillows that are used by commercial establishments, in airplanes, or the like, where health and sanitation regulations may require that the pillow be secured within the pillow case. Some pillow cases and pillow shams have been constructed with flaps that are adapted to be stretched over the outward facing corners of the pillow after it is inserted. Such pillow cases are more expensive to produce, are difficult to use, and require additional seams that may rip or tear with repeated use. Pillow cases are therefore needed that are adapted to releasably secure pillows within pillow cases with minimal time, effort and expense.